A method for preparing a low-cyclic antibacterial modified silicone oil

Abstract

This invention discloses a method for preparing low-cyclic antibacterial modified silicone oil. Using polyetheramine and terminal epoxy silicone oil as starting materials, the mixture is reacted fully in a solvent environment to obtain polyether silicone oil with double-terminated epoxy groups. Subsequently, oligo-chitosan obtained through degradation and acidification is added, and the reaction yields the low-cyclic antibacterial modified silicone oil. This invention has advantages such as high operability, energy saving, and low cost, making it suitable for industrial production. Furthermore, the prepared low-cyclic antibacterial modified silicone oil exhibits good antibacterial properties, strong wash resistance, good hydrophilicity, and biodegradability, making it suitable for use as an additive in daily chemical products and in the post-treatment of textile fabrics.

Description

Technical Field

[0001] This invention belongs to the field of antibacterial material preparation technology, specifically relating to a method for preparing a low-cyclic antibacterial modified silicone oil. Background Art

[0002] Textiles are highly susceptible to bacterial growth and are a significant source of disease transmission. Therefore, antimicrobial finishing of textiles is of paramount importance. Antimicrobial textiles prevent fabrics from being contaminated by microorganisms, thus preventing the spread of infectious diseases, ensuring human safety and health, and providing comfortable wear. They also reduce cross-infection in public environments and possess certain hygiene and health care functions. Antimicrobial textiles have a wide range of applications, including home textiles, underwear, sportswear, interior decorations, hospital uniforms, food processing and pharmaceutical work clothes, patient gowns, and packaging materials.

[0003] There are two main methods for antibacterial treatment of textiles. One method involves directly treating the fabric fibers with antibacterial substances, attaching the substances to the fabric surface through sedimentation. For example, Chinese patent CN201410164116.9 uses chitosan and titanium dioxide as antibacterial raw materials to treat wool fabrics. The treated fabric has an antibacterial effect, but the chitosan does not bind tightly to the fabric and is easily washed off. The second method involves synthesizing a finishing agent with antibacterial properties and then treating the fabric. For example, Chinese patent CN116640314A uses long-chain alkylamines and terminal epoxy polyether silicone oil to synthesize quaternized silicone oil under acidic conditions, and then combines the silicone oil with the fabric through finishing to obtain a fabric with antibacterial properties.

[0004] Currently, commonly used antibacterial substances are divided into non-biological and bio-based types. Non-biological antibacterial materials include organic compounds (such as quaternary ammonium compounds and polydimethylhexanone) and metal-based materials (such as silver, zinc, titanium, and their oxides and salts). Bio-based antibacterial materials include chitosan, tea polyphenols, menthol, and betaine. With increasing international emphasis on environmental protection, biodegradable antibacterial materials have become a focus of attention. Chitosan, due to its biodegradability, biofriendliness, availability, antibacterial properties, and reactivity, is very suitable for use as an antibacterial material for textiles.

[0005] Chinese patent CN118110032A discloses a chitosan composite antibacterial fabric, its preparation method, and its application. The method involves immersing the fabric in a chitosan acetate solution, followed by shaking and drying to obtain chitosan fibers / fabric. The immersion process is then repeated, followed by transfer to a sulfate / phosphate aqueous solution, washing with deionized water, and drying to obtain the target fabric. Using chitosan coatings with different hydrophilic and hydrophobic properties satisfies the fabric's antibacterial, cell activity, hemolytic, and coagulation properties, while retaining the fabric's original shape, breathability, and flexibility. However, because the chitosan is coated onto the fabric surface through deposition and drying, the bonding is not tight, resulting in poor wash resistance.

[0006] Chinese patent CN105088774B discloses a method for preparing long-lasting antibacterial fabrics. This method involves complexing nano-silver with chitosan and controlling the isoelectric point of the system to allow the nano-silver to complex and deposit onto fibers using a "messenger" technology. This allows the nano-silver to accumulate in large quantities on the fabric surface, achieving long-lasting antibacterial effects. However, concerns remain regarding the biosafety of nano-silver, and the high cost also hinders the widespread application of this technology.

[0007] Chinese patent CN118087113A discloses an antibacterial yarn and its preparation method. First, a metal material modified with an epoxy silane coupling agent is loaded onto wool via padding / magnetron sputtering. Then, dopamine, chitosan, acrylic acid, and a crosslinking agent are mixed uniformly to obtain a chitosan mixture. This mixture is then used to impregnate the silver-loaded wool, followed by rolling, drying, and finally immersion in a mixture of isohexyl glycol and dipropylene glycol. After reaction, the mixture is washed and dried to obtain chitosan-loaded silver wool. This is then combined with bamboo fiber to obtain the antibacterial yarn. This preparation method involves cumbersome steps, and dopamine is very expensive, making it unsuitable for industrial production.

[0008] Therefore, it is necessary to develop an antibacterial substance that can improve washability, reduce costs, and simplify the process while ensuring good antibacterial effects. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a method for preparing low-cyclic antibacterial modified silicone oil. The method involves preparing epoxy-terminated polyether silicone oil using polyether amine and terminal epoxy silicone oil, then reacting it with cationic oligochitosan to obtain the low-cyclic antibacterial modified silicone oil. When used for fabric treatment, this method can improve the antibacterial effect and washability of the fabric, and it also has advantages such as low cost and simple process, making it suitable for industrial production.

[0010] To achieve the above objectives, the present invention provides a method for preparing a low-cyclic antibacterial modified silicone oil, comprising the following steps:

[0011] (1) Dissolve polyetheramine and terminal epoxy silicone oil in a solvent and react to obtain epoxy group-terminated polyether silicone oil;

[0012] (2) Chitosan is dissolved in acid, an oxidizing agent is added, and the reaction yields oligochitosan;

[0013] (3) Dissolve the oligochitosan in acid to obtain cationic oligochitosan;

[0014] (4) Place the cationic oligochitosan into the polyether silicone oil obtained in step (1) and react to obtain low-cyclic antibacterial modified silicone oil.

[0015] Preferably, the molar ratio of polyetheramine and terminal epoxy silicone oil in step (1) is 1:1.8-2.5.

[0016] More preferably, the molar ratio of the polyetheramine and the terminal epoxy silicone oil is 1:2.0-2.2.

[0017] More preferably, the polyetheramine has a linear molecular structure with -NH2 groups at both ends of the chain segment and polyether segments in the middle, and a molecular weight of 200-3000; even more preferably, the molecular weight is 200-1000.

[0018] More preferably, the terminal epoxy silicone oil is a linear polysiloxane segment with double-ended epoxy groups, volatile matter <0.5%, and molecular weight of 400-40000; even more preferably, the molecular weight is 4000-20000.

[0019] Preferably, the solvent in step (1) is one or more of diethylene glycol butyl ether, dipropylene glycol butyl ether, and isohexyl glycol.

[0020] Preferably, the reaction temperature in step (1) is 40-125°C, and the reaction is protected with an inert gas.

[0021] More preferably, the reaction temperature is 70-90°C, and the inert gas is nitrogen.

[0022] Preferably, the mass ratio of chitosan, acid and oxidant in step (2) is 1:3:0.08; and the reaction temperature is 45-70℃.

[0023] More preferably, the acid is one or more of glacial acetic acid, carbonic acid, and propionic acid, with a pH of 5.0-6.5 and a mass fraction of 3-5%; even more preferably, the pH is 6.0-6.0.

[0024] More preferably, the degree of deacetylation of the chitosan is >90%.

[0025] More preferably, the degree of deacetylation of the chitosan is ≥95%.

[0026] More preferably, the oxidant is hydrogen peroxide.

[0027] Preferably, the molecular weight of the oligochitosan in step (2) is 2000-8000.

[0028] Preferably, the mass ratio of oligochitosan to acid in step (3) is 2:1.

[0029] Preferably, the dissolution time in step (3) is 1-12 hours.

[0030] More preferably, the acid is one or more of glacial acetic acid, carbonic acid, and propionic acid, with a pH < 5.0.

[0031] Preferably, the reaction temperature in step (4) is 30-100℃ and the reaction time is 1-8h; more preferably, the reaction temperature is 30-60℃.

[0032] The beneficial effects of the present invention are:

[0033] 1. By controlling the ratio of polyetheramine and epoxy silicone oil in the reaction, epoxy-terminated polyether silicone oil is obtained. This oil has a polyether siloxane segment with dual-terminated epoxy groups in the middle. On the one hand, it retains the reactivity of both ends; on the other hand, the amino group in the middle of the segment facilitates binding with groups on the fabric surface. After reacting the epoxy-terminated polyether silicone oil with oligochitosan, the presence of the polyether segments and oligochitosan makes the silicone oil more hydrophilic, facilitating its use. Simultaneously, chitosan, as a biomolecule, can be used as an antibacterial modifier and possesses biodegradable properties.

[0034] 2. By controlling the pH value of the acid used in the two acidification processes, different conditions required for chitosan depolymerization and cationization can be met. The free amino groups present in chitosan can react with H+ in the acid. + The reaction produces -NH 3+ When the pH value is between 5.0 and 6.5, the ionic strength of the solution is low. Due to the repulsive effect of the positive charge, the chitosan molecular chains unfold, increasing the number of attack sites for active oxidizing groups, which is conducive to the degradation reaction. However, when the pH value is less than 5.0, a large amount of -NH4+ will be produced. 3+ At this point, the system mainly consists of acetylamino groups, whose steric hindrance will prevent hydrogen peroxide from attacking the β-glycosidic bond and thus avoid degradation.

[0035] 3. Using degraded oligochitosan as the reactant monomer has several advantages: firstly, compared to chitosan, oligochitosan has better solubility and is easier to process; secondly, reducing the molecular weight of chitosan facilitates its attachment to polysiloxane segments through reaction; and thirdly, as the molecular weight of chitosan decreases, its antibacterial ability is improved.

[0036] 4. This invention uses the ring-opening condensation of polyetheramine and ultra-low volatile end-epoxy silicone oil to prepare low-cyclic antibacterial modified silicone oil. Compared with the traditional copolymerization method for synthesizing silicone oil and then removing low-boiling substances at high temperature / for a long time, the reaction is carried out at a lower temperature throughout the process, which can effectively retain the amino activity. The polyether segments in the system also make the product more hydrophilic, making the emulsification process more convenient and the treated fabric more skin-friendly. At the same time, the product meets the current international standards for low-cyclic silicone products, and the product can be applied in a wider range of fields. Detailed Implementation

[0037] The technical solution of the present invention will be further explained and described below with reference to specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0038] All quantities mentioned in the following examples are by weight.

[0039] Example 1: Preparation of Low-Ringness Epoxy Polyether Silicone Oil

[0040] (1) Take 100 parts of terminal epoxy silicone oil (molecular weight 2000), 22.5 parts of polyetheramine ED900 (the molar ratio of polyetheramine to terminal epoxy silicone oil is 1:2) and mix and dissolve them in 30 parts of diethylene glycol monobutyl ether to obtain a mixed solution;

[0041] (2) The mixed solution was then protected with nitrogen under normal pressure, stirred and heated to 80°C, refluxed and reacted for 3 hours to obtain epoxy-terminated polyether silicone oil; its yield was 98.90% and its viscosity was 118 cp.

[0042] Example 2

[0043] (1) Take 100 parts of terminal epoxy silicone oil (molecular weight 8000), 5.6 parts of polyetheramine ED900 (the molar ratio of polyetheramine to terminal epoxy silicone oil is 1:2) and mix them with 30 parts of dipropylene glycol butyl ether to obtain a mixed solution;

[0044] (2) The mixed solution was then protected with nitrogen under normal pressure, stirred and heated to 80°C, refluxed and reacted for 3 hours to obtain epoxy-terminated polyether silicone oil; its yield was 98.82% and its viscosity was 292cp.

[0045] Example 3

[0046] (1) Take 100 parts of terminal epoxy silicone oil (molecular weight 20000), 2.3 parts of polyetheramine ED900 (the molar ratio of polyetheramine to terminal epoxy silicone oil is 1:2) and mix them with 30 parts of isohexyl glycol to dissolve them and obtain a mixed solution;

[0047] (2) The mixed solution was then protected with nitrogen under normal pressure, stirred and heated to 80°C, refluxed and reacted for 3 hours to obtain epoxy-terminated polyether silicone oil; its yield was 99.16% and its viscosity was 1600cp.

[0048] Example 4: Preparation of oligochitosan

[0049] (1) Dissolve 1 part chitosan (95% degree of deacetylation) in an aqueous solution of 3 parts glacial acetic acid (pH=5.5) and stir until completely dissolved;

[0050] (2) Place the solution obtained in step (1) in a reactor, heat it to 50°C, then add 5 parts of hydrogen peroxide (w=0.02), and stir slowly and uniformly for 6 hours.

[0051] (3) The solution after the reaction was filtered and dried to obtain a pale yellow oligochitosan product with a weight-average molecular weight of 6.2 x 10⁻⁶. 3 The molecular weight distribution coefficient is 2.23.

[0052] Example 5

[0053] The method and steps are the same as in Example 4, except that the temperature in step (2) is changed to 80℃ to prepare a red oligochitosan product with a weight-average molecular weight of 5.6 x 10⁻⁶. 3 The distribution coefficient is 2.38.

[0054] Example 6

[0055] The method and steps are the same as in Example 4, except that the amount of hydrogen peroxide in step (2) is changed to 8 parts, and a pale yellow oligochitosan product with a weight average molecular weight of 5.8 x 10⁻⁶ is obtained. 3 The distribution coefficient is 2.12.

[0056] Example 7

[0057] The method and steps are the same as in Example 4, except that the temperature in step (2) is changed to 80℃ and the amount of hydrogen peroxide is changed to 8 parts. A yellow oligochitosan product with a weight average molecular weight of 5.6 x 10⁻⁶ is obtained. 3 The distribution coefficient is 2.14.

[0058] Example 8

[0059] (1) Dissolve 1 part chitosan (92% degree of deacetylation) in 3 parts of an aqueous solution of carbonic acid (pH=6.0) and stir until completely dissolved;

[0060] (2) Place the solution obtained in step (1) in a reactor, heat it to 65°C, then add 5 parts of hydrogen peroxide (w=0.02), and stir slowly and uniformly for 6 hours.

[0061] (3) The solution after the reaction was filtered and dried to obtain a pale yellow oligochitosan product with a weight-average molecular weight of 6.8 × 10⁻⁶. 3 The molecular weight distribution coefficient is 2.54.

[0062] Example 9

[0063] (1) Dissolve 1 part chitosan (98% degree of deacetylation) in an aqueous solution of 3 parts propionic acid (pH=6.0) and stir until completely dissolved;

[0064] (2) Place the solution obtained in step (1) in a reactor, heat it to 50°C, then add 5 parts of hydrogen peroxide (w=0.02), and stir slowly and uniformly for 6 hours.

[0065] (3) The solution after the reaction was filtered and dried to obtain a pale yellow oligochitosan product with a weight-average molecular weight of 5.2 × 10⁻⁶. 3 The molecular weight distribution coefficient is 2.28.

[0066] Example 10: Preparation of Low-Ring-Concentration Antibacterial Modified Silicone Oil

[0067] (1) Take the oligochitosan prepared in Example 6 and place it in glacial acetic acid solution (pH=4.5), stir and acidify for 1 h to obtain cationic oligochitosan;

[0068] (2) Under nitrogen protection, the epoxy-terminated polyether silicone oil prepared in Example 2 was placed into the reactor, heated to 50°C and stirred. While stirring, the cationic oligochitosan prepared in step (1) was added. After reacting for 8 hours, the low-cyclic antibacterial modified silicone oil was obtained.

[0069] Example 11

[0070] The method and steps are the same as in Example 10, except that the terminal epoxy polyether silicone oil is replaced with the one prepared in Example 2, and a low-cyclic antibacterial modified silicone oil is prepared.

[0071] Example 12

[0072] The method and steps are the same as in Example 10, except that the terminal epoxy polyether silicone oil is replaced with the one prepared in Example 3, and a low-cyclic antibacterial modified silicone oil is prepared.

[0073] Example 13

[0074] The method and steps are the same as in Example 10, except that the glacial acetic acid solution in step (1) is replaced with a propionic acid solution with a pH of 4, and the acidification time is changed to 5h; the reaction temperature in step (2) is changed to 30℃, and low-cyclic antibacterial modified silicone oil is prepared.

[0075] Example 14

[0076] The method and steps are the same as in Example 10, except that the glacial acetic acid solution in step (1) is replaced with a carbonic acid solution with a pH of 3, and the acidification time is changed to 12h; the reaction temperature in step (2) is 100℃ and the reaction time is 1h, and low-cyclic antibacterial modified silicone oil is prepared.

[0077] Comparative Example 1

[0078] (1) Take chitosan and place it in glacial acetic acid solution (pH=4.5), stir and acidify for 1 hour to obtain cationic chitosan;

[0079] (2) Under nitrogen protection, the epoxy-terminated polyether silicone oil prepared in Example 2 was placed into the reactor, heated to 50°C and stirred. While stirring, the cationic chitosan prepared in step (1) was added, and the reaction was continued for 8 hours to obtain the modified silicone oil.

[0080] Comparative Example 2

[0081] Under nitrogen protection, the epoxy-terminated polyether silicone oil prepared in Example 2 was placed in a reactor, heated to 50°C and stirred. While stirring, the oligo-chitosan prepared in Example 4 was added, and the reaction was continued for 8 hours to obtain the modified silicone oil.

[0082] Comparative Example 3

[0083] (1) Take 100 parts of terminal epoxy silicone oil (molecular weight 8000, volatile content > 1%) and 8.4 parts of polyetheramine ED900 and mix them with 30 parts of diethylene glycol monobutyl ether to obtain a mixed solution;

[0084] (2) The mixed solution was then protected with nitrogen under normal pressure, stirred and heated to 80°C, refluxed and reacted for 3 hours to obtain epoxy-terminated polyether silicone oil; its yield was 98.46% and its viscosity was 254 cp.

[0085] (3) Take the oligochitosan prepared in Example 6 and place it in glacial acetic acid solution (pH=4.5), stir and acidify for 1 h to obtain cationic oligochitosan;

[0086] (4) Under nitrogen protection, the epoxy-terminated polyether silicone oil prepared in step (2) is placed into the reactor, heated to 50°C and stirred. While stirring, the cationic oligochitosan prepared in step (1) is added, and the reaction is continued for 8 hours to obtain the modified silicone oil.

[0087] Comparative Example 4

[0088] The method and steps were the same as those in Comparative Example 3, except that the molecular weight of the terminal epoxy silicone oil was changed to 20,000 and the amount of polyetheramine ED900 was changed to 1.1 parts. The modified silicone oil was prepared with a yield of 99.08% and a viscosity of 1527 cp.

[0089] Example 15 Emulsification Application

[0090] (1) The modified silicone oils prepared in the above examples and comparative examples were tested for their cyclic content by gas chromatography. The results are shown in Table 1.

[0091] (2) Take the modified silicone oil prepared in the above examples and comparative examples, and the epoxy-terminated polyether silicone oil prepared in the above examples, add glacial acetic acid and stir to emulsify. Water is gradually added during the stirring and emulsification process until the appearance of the emulsion is uniform and stable; wherein the amount of glacial acetic acid used is 2wt% of the solid content of the emulsion.

[0092] (3) Immerse the cotton fabric in the emulsion obtained in step (1) for 5 minutes, then squeeze out the excess water, dry it in a dryer at 165°C for 1 minute, and place it at room temperature for half an hour to test the feel of the cotton fabric. The feel test items are softness and smoothness. The results are shown in Table 2.

[0093] (4) Take the cotton cloth obtained in step (3) and test its antibacterial effect according to the People's Republic of China National Standard GB / T 20944.3-2008. The results are shown in Table 3.

[0094] Table 1. Cyclic content of modified silicone oils

[0095]

[0096] Table 2. Application feel of silicone oil

[0097]

[0098] Note: The feel rating is divided into 1-5 levels, with 5 being the best and 1 being the worst.

[0099] Table 3 Antibacterial properties of silicone oil

[0100]

[0101] As can be seen from Table 1, the contents of D4, D5, and D6 in the low-cyclic antibacterial modified silicone oil products prepared in Examples 10-14 and Comparative Examples 1, 2, and 4 are all less than 1000 ppm, which complies with relevant international laws and regulations. However, the cyclic content of the modified silicone oil prepared in Comparative Example 3 significantly exceeds the limit, indicating that the volatile components of the selected end-epoxy silicone oil have a very significant impact on the cyclic content in the system.

[0102] As shown in Table 2, for epoxy-terminated polyether silicone oil, the higher the viscosity, the better the smoothness and the worse the softness of the treated cotton fabric. However, the cotton fabric treated with low-cyclic antibacterial modified silicone oil did not show a significant change in hand feel. This is because under nitrogen protection and low-temperature reaction conditions, the amino groups in the system were not destroyed and could still adhere to the surface of the fabric. At the same time, the hydroxyl groups contained in chitosan could also enhance the adhesion to the surface of the cotton fabric. The hand feel of the cotton fabric treated with the modified silicone oil prepared in Example 14 decreased. This is because some amino groups were destroyed during the high-temperature treatment. In addition, the hand feel of the cotton fabric treated with the modified silicone oil prepared in Comparative Example 4 decreased significantly. This is because the proportion of polyether amine was too low, resulting in fewer amino groups in the product, which could not adhere to the surface of the fabric.

[0103] As shown in Table 3, the epoxy-terminated polyether silicone oil prepared from polyetheramine and terminal epoxy silicone oil does not possess antibacterial properties, while untreated chitosan exhibits antibacterial properties, but its wash resistance is poor, and the antibacterial performance decreases significantly after washing. The cotton fabric treated with the low-cyclic antibacterial modified silicone oil prepared in Examples 10-12 has a higher antibacterial rate and better wash resistance than the untreated chitosan. This is because the antibacterial performance of chitosan is affected by its molecular weight; the higher the molecular weight, the worse the antibacterial performance. Furthermore, the wash resistance of the cotton fabric treated with the low-cyclic antibacterial modified silicone oil prepared in Examples 10-12 decreases sequentially. This is because as the molecular weight of the terminal epoxy polyether silicone oil increases, the reactivity decreases, and some chitosan fails to attach to the siloxane backbone, resulting in poor adhesion to the fabric and easy detachment during washing. The antibacterial properties of the cotton fabric treated with the modified silicone oil prepared in Comparative Example 1 decreased before and after washing. This is because the undegraded chitosan molecules are large, have poor antibacterial properties, and are difficult to graft onto the siloxane segments. In contrast, the cotton fabric treated with the modified silicone oil in Comparative Example 2 showed good antibacterial properties before washing, but the antibacterial properties decreased significantly after washing. This is because the un-acidified oligochitosan is difficult to graft onto the siloxane backbone and is easily detached during washing. The wash resistance of the cotton fabrics treated with the modified silicone oil in Comparative Examples 3 and 4 decreased. The decrease in Comparative Example 3 was due to the excessive participation of amino groups in the end-capping process, making it difficult for the oligochitosan to react. In Comparative Example 4, the large molecular weight of the epoxy silicone oil and the low amount of polyetheramine made it difficult for the oligochitosan to react onto the siloxane segments, and some silicone oil also failed to adhere to the fabric, ultimately leading to reduced wash resistance.

Claims

1. A method for preparing a low-cyclic antibacterial modified silicone oil, characterized in that: Includes the following steps: (1) Dissolve polyetheramine and terminal epoxy silicone oil in a solvent and react to obtain epoxy group-terminated polyether silicone oil; (2) Chitosan is dissolved in acid, an oxidizing agent is added, and the reaction yields oligochitosan; (3) Dissolve the oligochitosan in acid to obtain cationic oligochitosan; (4) Place the cationic oligochitosan into the polyether silicone oil obtained in step (1) and react to obtain low-cyclic antibacterial modified silicone oil; The molar ratio of polyetheramine and terminal epoxy silicone oil in step (1) is 1:1.8~2.

5.

2. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The solvent in step (1) is one or more of diethylene glycol butyl ether, dipropylene glycol butyl ether, and isohexyl glycol.

3. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The polyetheramine has a linear molecular structure with -NH2 groups at both ends of the chain segment and a polyether chain segment in the middle, with a molecular weight of 200-3000; the terminal epoxy silicone oil is a linear polysiloxane chain segment with double-ended epoxy groups, with a volatile content of <0.5% and a molecular weight of 400-40000.

4. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The reaction temperature in step (1) is 40-125℃, and an inert gas is used for protection during the reaction.

5. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The mass ratio of chitosan, acid and oxidant in step (2) is 1:3:0.08; the reaction temperature is 45-70℃.

6. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 5, characterized in that: The acid is one or more of glacial acetic acid, carbonic acid, and propionic acid, with a pH of 5.0-6.5; the oxidant is hydrogen peroxide.

7. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The molecular weight of the oligochitosan in step (2) is 2000-8000.

8. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The mass ratio of oligochitosan to acid in step (3) is 2:1; the dissolution time is 1-12h.

9. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 8, characterized in that: The acid is one or more of glacial acetic acid, carbonic acid, and propionic acid, with a pH < 5.

0.

10. The method for preparing a low-cyclic antibacterial modified silicone oil according to claim 1, characterized in that: The reaction temperature in step (4) is 30-100℃, and the reaction time is 1-8h.

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